ᐅ Crack in basement ceiling is getting larger—who should I contact?

Hello everyone, we bought a house last year that was built in 1987. Since we moved in, there has been a crack in the basement ceiling that is getting bigger. Who would be the best or first point of contact for this? A structural engineer or a building inspector?

What I mainly want to know is whether the crack could be dangerous or if it’s just something that can be simply filled in.

I would first shore it up temporarily as a precaution and then have a structural engineer come to assess it.

What does ".gets bigger and bigger." mean?
Was it 50cm long (20 inches) and is getting longer?
Or was it 2mm wide (0.08 inches) and is now 1cm wide (0.4 inches)?

What’s breaking there? Concrete, plaster, insulation?
No chance to take a photo?

At first, the crack was more like a slight indication, but it has been getting wider over time. There was also a crack at the bottom at the beginning, and now both cracks are essentially connected.

The ceiling also does not appear to be level; one panel seems to be slightly lower than the other.

35 years old, nothing should still be shifting. Have you made any structural changes? The concrete slab has already been patched before. The reinforcing steel will probably hold it together, but it still needs to be checked.